Nail-Patella Syndrome is a rare genetic disorder that often results in deformities of the kneecaps, thumb and finger nails, elbows, pelvis, and ankles. The syndrome is named for the two most common manifestations: deficiency of the nails and the patellas (kneecaps). However, Nail-Patella Syndrome affects the entire body. Joint contractures are a common feature of this syndrome, and many affected individuals develop arthritis of their joints.
Abnormalities of the nails is the most common feature in individuals with Nail-Patella Syndrome. The thumbnails are more severely affected, and deformities of the fingernails occur more often than deformities of the toenails. The nails of affected individuals are poorly developed, with only a small piece of nail present or sometimes with no nail at all. The nails may also be discolored or triangular shaped (rather than the normal crescent shape).
The second most common feature of Nail-Patella Syndrome is deformity of the kneecaps (patella). The kneecaps are smaller than normal or absent in some cases. They are also typically irregularly-shaped, and dislocation of the patella occurs frequently. Affected individuals often have similar deficiencies of the elbow and hip joints. Individuals with elbow deformities usually have difficulty extending their arms straight and rotating their forearms. In the hip, affected individuals may outgrowths in the iliac bone.
Other areas of the body may also be affected in Nail-Patella Syndrome. Glaucoma of the eyes and kidney diseases, such as proteinuria and nephritis, may also be present.
Nail-Patella Syndrome is quite rare, affecting 1 in 50,000 individuals. The syndrome is linked to mutations in the LMX1B gene, which codes for a protein that binds to the DNA and regulates other genes. This protein is thought to be important to the development of limbs, the kidneys, and the eyes in early development. Nail-Patella Syndrome is inherited in an autosomal dominant fashion, meaning only a single copy of the gene is required to express symptoms.
At the Paley Institute, we treat the orthopedic manifestations of Nail-Patella Syndrome, namely deformities and deficiencies in the knee, elbow, hip, and ankle joints.
The primary complaint of those with Nail Patella Syndrome is the deformity of the knee, specifically the dislocation of the patella. To correct this, Dr. Paley will first reduce the tibia on the fibula with application of an external fixator. A circular external fixator (Ilizarov or TSF) is preferred since it can perform three-dimensional correction.
A similar approach can be performed on other joints that may be deficient due to Nail Patella Syndrome. The treatment strategy will follow these steps:
- Gradual distraction of the affected joint with external fixator
- Osteotomy to correct and realign the joint
- Soft tissue releases to correct contractures
- Limb lengthening to correct limb length discrepancies
At the Paley Institute, we have successfully performed limb deformity correction and limb lengthening on patients with Nail Patella Syndrome, with excellent results.